1. Field of the Invention
The present invention relates to a dispensing apparatus and more particularly to a dispensing apparatus which is particularly well suited to the application of fluid medication employing a needle as, for example, in the intradermal and subcutaneous injection of local anesthetics in the manner of a syringe.
2. Description of the Prior Art
The application of fluid substances, and more particularly fluid medications such as anesthetics applied with syringes, in such working environments as doctors' offices, hospitals, emergency facilities, other medical care facilities and the like is plagued by a host of difficulties which both detract from the ease and dependability with which such substances can be applied and from the safe and successful use of those substances. Thus, for example, while the use of syringes of a wide variety of types has long been known in the administering of fluid substances and while advances have been made in the construction and operation of such syringes, including the use of disposable syringes, such prior art devices are both inefficient to use, susceptible to improper or inexact usage and in some instances dangerous. Particularly, under emergency conditions or otherwise in those instances in which the circumstances of usage require expeditious procedures, such prior art devices are substantially less effective than would be desired.
In the case of conventional syringes, the user must locate a vial containing the required medication, attach a needle to the syringe, insert the needle into the vial, withdraw the plunger of the syringe until the desired volume of medication is received in the barrel of the syringe, remove the needle from the vial, recap the needle to remove it from the syringe, attach a new needle, expel any residual air within the barrel of the syringe from the syringe through the needle and subsequently administer the injection in the specified quantity. Subsequently, the syringe must be disposed of in accordance with specified disposal procedures. Depending upon the particular procedure performed, the needle is replaced after any contact with a nonsterile, or possibly nonsterile, environment. Thus, for example, the needle is replaced after withdrawal of the medication from the vial and prior to injection into the patient because the vial stopper may be nonsterile. In addition, typically, a smaller diameter needle is employed for the injection than for withdrawal of medication from the vial. These operations are not only time consuming and thus inefficient, but also conducive to error and thus hazardous, particularly under the tension of the circumstances under which the user must often operate.
In this regard, changing needles in conventional syringes requires that the user recap the needle. This is hazardous due to the risk of puncture by inadvertent contact with the needle. More over, conventional syringes are frequently used with multi-dose medication vials which can become contaminated and serve as a source of iatrogenic infection with such contagious agents as the Acquired Immune Deficiency Syndrome and Hepatitis viruses. Thus, the capability of conventional syringes to be refilled constitutes a means by which health hazards are perpetuated.
Therefore, it has long been known that it would be desirable to have a dispensing apparatus operable efficiently, safely and dependably to administer fluid substances such as medication under even the most aggravated emergency procedures requiring minimal manual dexterity by the user and therefore minimizing the opportunity for error while being as convenient as possible to leave the attention of the user available for other concerns.